Improvement in the manufacture of steel



' UNITED STATES PATENT OFFICE.

JULIUS BAUR, OF NEW YORK, N. Y.

IMPROVEMENT IN THE MANUFACTURE OF STEEL.

Specification forming part of Letters Patent No. 49.495, dated August.1865.

To all whom it may concern:

Be it known that I, J ULIUs BAUR, of the State, county, and city of NewYork, have invented a new and useful Improvement; in the Manufacture ofSteel; and I hereby declare that the following is a full, clear, andexact description of the same.

No drawings accompany this specification,

for the reason that the nature of the case does not admit of drawings.

This invention is applicable both to the in akin g of steel in theordinary steel-makers crucibles and to making it in the large way bywhat is known as the Bessemer or pneumatic stance, in any form whateverin the making of steel, and at the same time to produce as good orbetter quality of steel than can be made bytheuseofanyofsaidlast-referred-tosubstances, whether said substances beused alone or combined together.

It is believedthat chromium does not exist in nature in a pure metallicstate, but only in the form of an oxide of chromium or chrome ore; andin order to obtain it in the proper condition to be made available by myprocess it is necessary to reduce the chrome ore to metallic chromium.For this purpose I efiect the reduction by taking the requisite quantityof chrome ore and presenting to the oxide contained in it a sufficientamount of carbon to remove the oxygen and leave the chromium in a pureor nearly pure metallic state. I prefer,

in doing this, to use a quantity of carbon somewhat in excess ofwhatever quantity of chrome i ore I operate upon, in order that I maybeas be reduced, they may be heated, if desired, in a paddling-furnace,blast-furnace, or furnace or vessel of any other suitable description.Upon being heated thecarbon will combine with the oxygen and set freethe metallic chromium, in the formof shots and small lumps,b v areaction well known to chemists. After the metallic chromium has beenthus produced it must by sifting and Washiug,'or other suitable means,be thoroughly separated from the small adhering particles of the coalused in heating the contents of the reducing-vessel, andwhen thusseparated I take the requisite quantityof it, together with therequisite quantity of carbon, and add it in the crucible or other vesselto the iron to be converted into steel. plain what this requisitequantity will be I will state my respective methods of procedure inmaking different kinds or qualities of steel:

For tool-steel of superiorquality I take about five pounds of themetallic chromium and about five ounces of powdered charcoal to everyonehundred pounds (more orless) of puddled, iron of proper steel-makingquality.

Instead of the powdered charcoal whitepigiron or other suitablecarbonaceous matters may be employed; but when I use the white pig-ironI take about eight pounds of it to every one hundred pounds (more orless) of puddled iron, theproportion ofchromium remaining the same: Ifpure graphite be employed asa carbonizer, I use the same quantity as ofpowdered charcoalnamely, about five ounces. lf bonedust be used, I takeabout two ounces of it combined with about three ounces of powderedcharcoal to every hundred pounds (more orless) of puddled iron andeveryfive pounds of metallic chromium. From these examplesit will be evidentthat when still other suitable carbonaceous matters are desired tobeeniployed e the proper proportions and mixtures for each canreadily beascertained by thoseskilled in,

e art.

In melting the metallic chromium and pudd diron, as above described, Iuse about ten sure as possible to remove every particle of ore. I preferthat the chrome p M p, H epulverized or granulated as fineiy asposs HethefinerthebetteP-and that he charcoal which furnishes the carbonshould then to put them, thus mixed, into an ordinary crucible; or, iflarge quantities are requiredto p y sof common salt, or fluor-spar, orabout x ounces of cryolite, or any other suitable fink, The cryolite is,however, somewhatlia 1e injure the meltiug-vesselby reasonjof erilextent.

rfa good quality To exof spring-steel lit q i recommend about threepounds of metallic chromium andabout four ounces of powdered charcoal toevery hundred pounds (more or less) of puddled iron, the flux to be usedbeing the same as above mentioned.

If white pig-iron be employed as a carbonizer for spring-steel in placeof powdered charcoal, I take about six pounds of it to every hundredpounds of puddled iron, and if still other carbonizers are desired, theproportions and mixtures for them may be determined from the examplesabove stated in reference to toolsteel.

For a quite low steel I employ about three pounds of chromium and aboutone ounce of charcoal to each one hundred pounds (more or less) ofpuddled iron, the flux remaining the same as'specified above. If whitepig-iron be used for the carbonizer of this low steel, I take about onepound and a half of it, and for other carbonizers I determine theproportions and mixtures in the manner above directed.

Instead of using puddled iron cast-iron maybe employed; but this,ofcourse, will produce a poorer steel. When cast-iron is employed it willbe necessary to use oxide of iron with it in order to remove the excessof carbon in the cast-iron over what is required for steel. This oxideof iron I employ either by itself or in the form of a hematite ormagnetite iron ore but if ore be used it must be very pure. I prefer toremove, by the oxide of iron, so much of the carbon in the cast-ironthat there shall be only about one and one-half per cent. of carbonremaining in it when tool-steel is to be made, and only about onepercent. when spring-steel is to be made, and only about onequarter to halfof one per cent. when low steel is to be made.

It will of course be understood that when cast-iron is used no charcoalor other additional carbonizer is required. It will also be understoodthat the same fluxes are to be used with cast-iron as with puddled iron.

My method has been thus far described as applicable to the making ofsteel in crucibles; but when it is desired to make steel in largequantities or masses substantitally the same mode of procedure may beadvantageously employed in reverberatin g furnaces, or in any other kindof furnace or vessel in which the fuel does not come in contact with thecharge to be converted into steel.

When thus making steel in large quantities I employ the same proportionsof the metallic chromium and of fluxes asIhave already specified for usein crucibles; but I employ the chromium in a different form, and,instead of puddled iron, I take cast-iron, which, in the process ofmaking the steel, should be decarbonized by the now well-knownBessemer'or pneumatic process,the chromium uniting with the iron in thecourse of the operatgan, and having the effect of greatly improiing thequality of steel which could be made by the pneumatic process alonewithout such union,

and thus constituting a highly beneficial substitute for spiegeleisen,franklinite, or a triple compound of iron, carbon, and manganese, whichhave heretofore been deemed essential to be used in connection with thepneumatic process. 7

To carry out this part of my improvement I prefer, previous to unitingthe chromium with the charge of melted iron in the pneumatic converter,to prepare it in the form of pigs, which shall consist of a triplecompound of iron, carbon, and metallic chromium. For this purpose Iprefer to take about four hundred pounds of chrome ore to about sixhundred pounds of a good hematite or magneticiron ore, free, or nearlyfree, from sulphur and phosphorus, and, after finely powderin g orgranulating these ores, to mix them thoroughly together and smelt themin an ordinary blast or onpola furnace in the manner usually practicedin smelting iron ores, and after the smelting has been performed I runthe melted metal into pigs in the common way. I prefer that thecomposition of these chromium pigs, as they maybe termed, shall be suchthat they shall consist of, say, from fourteen to eight een per cent. ofmetallic chromium, about seventy per cent. of iron, and from aboutfourto about six per cent. of carbon. The propor tions of four hundredpounds of chrome ore to six hundred pounds of the hematite. or magnetiteore will usually yield about the abovestated percentages of metallicchromium and iron in the pigs; but in order to secure the above-statedpercentage of carbon in the pigs it is necessary to observe the natureof the hematite or magnetite ores operated upon and how much carbon theparticular ore used con tains, and when this is known sufficient carboncan be removed or introduced during the operation of smelting, as wellknown to iron masters, to make the resulting amount of carbon in thepigs the percentage above specified. After these chromium pigs or triplecompound of iron, carbon, and chromium have been thus prepared, Iintroduce the requisite quantity of them into the pneumatic converter inthe manner and at that stage of the process at which spiegeleisen orfranklinite are now usually added. The proportions of this triplecompound which I prefer are from six to ten or twelve per cent., orthereabout, of the said triple compound to the charge of metallic ironin the con verter. These proportions may, of course, be varied accordingto the quality of steel required. For instance, about six per cent. ofthe triple compound will produce a good low steel, and about ten percent. will produce a good high steel, and intermediate grades of softand hard steel may be produced betweenthese extremes by varying thepercentage of the triple compound, according to the option of theoperator.

It will,of course, be understood thatin using myinvention in makingsteel in crucibles other grades and qualities of steel of differentdcgrees of hardness can be made by varying the proportions of thechromium and carbon employed with the iron; but the examples I havegiven will answer a good purpose, and will serve to illustrate myimprovement.

The use of my invention in connection with the pneumatic process will befound to entirely obviate the difficulties heretofore met with inmakingsteel by that process on account of such steel proving more or lessincapable of extension by hammering or rolling at any temperature, or onaccount of the bars formed from it having cracks or flaws in them, orbeing sometimes hot short and sometimes cold short, or possessing otherdefects.

I do not confine myself to the above-described method of producing thechromium pigs or triple compound of iron, carbon, and chromium, as thesame may be produced in other modes; but the one which I have specifledwill be found successful and will exemplify my improvement.

It will be observed that in this process of making or improving steel Idispense entirely with manganese, tungsten,(wolfram,) titanium,

or other analagous substances, and I believe that I am the first toestablish the fact that metallic chromium can be used practically inmaking steel for all purposes, and also the first to show that it can besuccessfully used alone and without being combined with any of the othersubstances named for producing steel of a superior excellence.

Having thus described my improvements, what I claim as new, and desireto secure by Letters Patent, is--- 1. Combining metallic chromium withiron for the purpose of producing or improving steel in crucibles,substantially in the manner set forth.

2. Combining metallic chromium with iron for the purpose of producing orimproving steel made by the pneumatic process, substantially in themanner set forth.

3. A triple compound of iron, carbon, and

chromium, substantially such as and for the purposes set forth.

JULIUS BAUB.

Witnesses:

M. M. LIVINGSTON,

J. W. BUTLER.

